Eliminating effect of variations in current supplied to audions



May 20, 1930. e. B. cRousE 1,759,545

ELIMINATING'EFFECT OF VARIATIONS IN CURRENT SUPPLIED TO AUDIONS Filed Aug. 22, 1924 6 Sheets-She'ek 1 TIME .INVENTOR fllzlligif A'ITO G. B. CROUSE ELIMINATING EFFECT OF VARIATIONS IN CURRENT SUPPLIED TO AUDIONS Filed Aug. 22,. 1924- 6 Sheets-Sheet May 20, 1930.

" INVENTOR a/zf; if

May 20, 1930. c;.- a. CROUSE ELIMINATING EFFECT OF VARIATIONS IN CURRENT SUPPLIED TO AUDIONS Filed Aug. 22, 192A 6 Sheets-Sheet 3 i INVENTOR- May 20, 1930; G. B. cRousE i 1,759,545

ELIMINATING EFFECT OF VARIATIONS IN CURRENT SUPPLIED T0 AUDIONS Filed Aug. 22, 1924 6 Sheets-Sheet 4 i INVENTOR gin I Wit/a1 ift ATTO% May 20, 1930. CROUSE 1,759,545

ELIMINATING EFFECT OF VARIATIONS IN CURRENT SUPPLIED TO AUDIONS Filed Aug. 22, 1924 6 Sheets-Sheet 5 INVENTOR @541.

May 20, 1930.

G. B. CROUSE ELIMINATING EFFECT OF VARIATIONS IN CURRENT SUPPLIED TO AUDIONS Filed Aug. 22, 1924 6 Sheets-Sheet 6 4 INVENTOR 69- 11 525 A t EY I Patented May 20, 1930 a j I U I-Tao STATES me rates-ff f GEORGE .LB. c'RoUsEQoF wooncnrrr nnw' JERSEY, AssIGNoa, BY MEsnE Assisti- .MENTS, 22o CONNER caotrsn coarserron i ELIMINATING 0F VARIATIONS IN CURRENT SUPPLIED TO AUDION S Applieation filediAugust 22, 1924.' Serial 310.733.558.

The invention relates to eliminating in the output circuit of an audion the effects of variations in current supplied to its elements.

Recognizing the desirability and advantages of being able to supply the audions of a radio receiver directly from lighting circuits Without the use of batteries many inventors have obtained patents for arrangements intended to accomplish this purpose, but for one reason or another none of the patented arrangements with which I am. familiar provides a current supply which is absolutely free from all alternating current components or short period variations, such as is re uired for the satisfactory operation of an ions,

particularly when used as detectors'and as amplifiers in radio receivers." It is therefore the usual practice tojsupply the currentfor the audions of radio receivers from primary or secondary batteries, but theirfdisadvantages are many and well known, particularly to those who have had occasionto use them.

In my co-pending application Serial No. 680,096, filed December 12, 1923, there is disclosed a method of filtering electric currents to provide a direct current supply for audions which is free from short period variations,

such as occur when alternating current is rectified or when direct current is generated by a dynamo having a col nmutator. This is accomplished'by causingthe current to be filtered to flow in parallel-paths and connect ing the load circuit across these paths at points of substantially equal alternating current potential but of unequal direct current potential, in the manner .ofv a Wheatstone bridge having inductances in its four arms and condensers in two opposite arms, the bridge being balanced for alternating currents or short period variations. The invention therefore makes possible the use of even rectified alternating current for supplying the cathodes and plates of audions, 7

It is an object of the present invention to eliminate in the output circuit of an au-dion the effects of variations in currentsupplied to its, elements, so that filters which fail to give current of the requisite smoothness may beused, or if the improved and satisfactory filter of my copending'application be used it may be madesmaller; In; other words, the lnventlon makes posslble the use for the cathodes and plates of audions of current which contains apercentage of short period variations or ripples, as they are usually called, whereas it has previously been neceshereinafter appear are attained by applying to one elementv of an audion variations in potential to oppose the effect on the output cir-' sary to use current absolutely free from such cuit caused by variations in the current supplied to this element and anotherelement The invention may be-practiced in several" ways. For instance, variations in potential may be applied to the plate to oppose the effect on the output circuit caused by variations in the plate circuitdue to variations in the current supplied to the cathode. -This may be done by placing in the plate circuitjinduotance and capacity so selected as to be anti-resonant at the frequency of the alternating, component of the supply.

Another way of practicing the inventioni s to increase the cathode effect by by-passing a resistance in series With the cathode by a a condenser, theby-pass circuit being made resonant at the frequency of the-supply ripple by an inductance in order that ther shall be no phase shift between the cathode and plate effect. I

A third way is'to increase the cathode efi fect sufficiently to cancel the plate eflectof the supply ripple by applying to t e ditional alternating potential.

The invention is also applicable to those arrangements in which the cathodes of the audions are supplied with alterr ti current,

but which arenot free from disturbances be- 3 cause the grld voltage-plate currentcharacter1st1c is not a straight hne n actual tubes.

The particular nature of the invention will appear most clearly from a description of certain preferred embodiments and their applications to radio receivers as shown in the accompanying drawings in which- Fig. 1 is an electrical diagram of an illustrat-ivc' character for use in explaining the invention, 1 r

grid an ad- I tion disclosed inFig;

, Fig. 2 shows theflpotential characteristics of the current supplied to the circuits of Fig; 8 is an electrical diagram similar to r thatofFig. l, but with ladditional elements in accordance vention',.; I H V V l I a similar diagram in accordance; ,fwi th, another*emhodiment:o'f the invention, with a third'emhodiment of the 1 invention,

with one embodiment o'fthe" in- Fig.4 is

Fig. 5 is a similar diagrain inaccordance Fig. 6 is an electrical diagram showing application of the embodiment of the inven "3 to a typical radiotreceiver,; 7' I v Fig.7 is a similar diagrajinshowingxanapplicationto a radioreceiver of the embodi ment' disclosed in Fig. 4, 1 r 3 V Fig. Sis a similar di'agram sh owing a similar application of the embodiment disclosed in Fig. 5, and T w Fig. 9 is an electrical diagram showingithe invention applied to-a radio'rece'iver in which l the filaments of the audionsare energizedby alternating current;

i For convenience thejgeneral principles of the invention will first, he explained in"connection with simplified diagrams, after which various applications of the invention to radio receivers-willhe described; 1 e y For the, purpose ofillustratinga current supply-containing i'ipplesfor short period variations there is 'shownfin F ig; 1 a battery I 1' of suitahlevoltage for operating the plate circuit -oi an audion and in series with which is analternating current generator 2 The potential suppliedatthe terminals-Send 4 V will therefore have the characteristics shown line A V and an" alternating current coma "1 ponent represented'hy the wavy line B,wh1ch in Fig. 2 and consisting of a direct current component represented by the straight broken is the ripple effect whichfit is the object of this invention to eliminate;

5'isthe filament, 6 the g id and plate I of'an 'audion. The filament is connected to the terminals 3 andthrough a resistance 8 of such magnitude as to reduce-the potential across the filament to suitable value. The

secondary 9 of a suitable input transformer is connectedin the usual way with one end to the rid 6 andtlie other end to the ne 'a end of the filament 5." The primary of this transformer is shown at The plate? is connected to the positive Vteri'nina'l' through a devlce lO'which is shown-asa telephone re-- ceiver, hut it"may he the primary of a repeaterfor connecting thecircuit to a second audionQ V V V Since the potential applied to the terminals 3 and t hasan alternating current component,

(B, Fig. 2) the'current passing through the filament Wlll also have an alternating current component, whichwill he in phase with the potential, since the filament circuit is en cern'ed,) but an inductance 11, a" capacity 12 tirely resistive. The alternating potential across the filament itself, which will onlybe'a small fractionof that across tli'e'term'lnals 3 and 4 since a large part of'it is dissipated 7 across the resistance 8 will cause a voltage to he appliedto the grid ln phase with the 1 drop, since-the gr dis connected. tofone end which will be feizact reproduction (neg lec'ting the small distortion- -efiects ofih'e a-udion) o f the alternatingpotential across" the filament, hut will'be 180 out of-phase with it. The alternating: potential at the terminals 3' andfl is applied directly to the plate circuit. and will cause a variation in the plate current which is in phase with the poten- 'of the filament lA' variationof the plate I 7 current cl 7 the audion i will therefore occur, I p 7 tial, except for the phase shift caused by the inductive device 10.

The effect of the filament ani ate the plate current due to the action ofthe'grid,

'- will. generally be 'smaller'than the direct effect of thevariations applied to the plate, as

may be seen by'applying some usual values v "The alternating.current potential across 7 mula - f Ebgw Since approximately only half of this 'po} 7 tential is-efiiectively appliedfto the grid, the" c effectonthe out-put or plate ,circuitis equivalent to avoltage on the plate of Tubes page 150 et seq.') p v By substituting the numerical values given above in this equatiomithere is obtained, a value of the platevoltage fluctuation due to} the filament, E'bf, will be given by the forf i J s V c 7 (see Van der Bijl, Thermionic. Vacuum the filament effectof 0.225 volts, whereas,,as stated previously, an alternating potential of r 1 volt is applieddirectly to the plate, bu t'in opposite phase to the filament effect.

In order that there shall he' noalter'nating current component in'theoutpuh'the alter;

hating potential applied directly to 'the platei must he made equal tothe plate'voltage variations due to the filament effect-,that is, to 0.225 volts for itheelectrical constants given above. This may 'he "done in several ways; One means of conveniently accomplishing it is shown in Fig.3 which is similar to Fig; 1,-

(as far as elements l'to '10 inclusive a'r'e'con'- and a resistance 13 are added to the plate circuit, The relative values of the capacity and inductance are such as to makethecombination.anti-resonant at the frequency of the alternating component ofthe supply. This combination, if properly designed as to internal losses, will reduce the alternating component of the plate supply to a value coni siderably below the value of the plate voltage '10 fluctuations due to the filament'eflect without shiftin its phase. The value can then be increased by the resistance 13 to that necessary to give zero alternating current in the output of the tube. When this adjustment is properly made, the plate circuit of the audion'has an effective impedance of infinity for the frequency of the supply ripple, andntherefore there is no phase shift effect due to the inductive device 10. 'Since' in practice, the frequency of the supply ripple is usually low, the condenser 12 serves as a lay-pass for the higher useful signal frequencies and prevents intercoupl ing at these frequencies; I

Another arrangement by which the inven tion Ina be racticed is shown in Fi 4 in which the parts identical with those of Fig. l ar'e i-dentically numbered. In this case, the resistance 8 in series with the filament is bypassed by means of the condenser 14. The

' cfiect ,ef capacity is to increase the filament eifect, instead of, as in the case of Fig.

3, reducing the plate effect. In order that there shall be 'no phase shift between the filament and plate effects, this capacity %bypass circuit is made resonant at the frequency of the supply ripple, by means of the induc- 'tance16. The amountvof current 'by-passed is adjusted by means of the resistance Still another way in which the invention may be practiced is shown in Fig. 5;, injwhich again the parts identical withthose of Fig. 1 are similarly numbered. In this arrange ment the filament effect is increased sufiiciently to cancel the plate effect of the supply ripple by applying to the grid an additional alternating potentiah'by means ofthe coil l7 placed in series with the filament lead and inductively related to; the input coil 9 in the grid circuit. The bracket in this figure indicates that the primary coil 9 ofthe secondary coil 9. f I

The above explanation in connection with Figs. 3, 4 and 5 shows three ways in which the invention may be practiced, in the first of which the balance is obtained. by reducing the plate circuit ripple, in the second, by increasing the alternating potential drop across the filament and in the third, by increasing the filament effect by means of the grid. It should be understood that in the numerical example given and in the embodiments shown, values havebeen'taken forthe quantities, which are usual for small tubes; In

- transformer is also inductively related to the the case of tubes having a high amplification constant, or having a high filament re I sistance, and'a low value direct current plate potential, so that the filament effect will northere is shown a common type of radioreceiver in which the current for both filaments and plates of the audions is supplied from an alternating current source, rectified and then fil-teredin accordance with the invention ofthe copending application hereinba fore referred to. In this figure and 21 are the terminals of an alternating current supply of usual commerical frequency and vol.- tage. Current from this source passages through the primary 22 of a transformer which has two secondary windings 23and 24 connected in the usual manner'to the rectifiers 25 and26, this arrangement being a common one for'rectifying both halves of the alternating current cycle. The rectifiedcurrent is then supplied to the storing condenser 27. To the terminalsof this condenser is connected a bridge circuit, comprising the inductances 28,30, 31 and 33 and the capacities 29 and 32, the action of which is fully described in the said copendingapplication. The filtered direct currentis taken off at the F: two mid connections 62. and 63, and passed through an inductance 34. Across the terminals 64 and 65 of the. receiver is connected a capacity 35. 9

Starting from the terminal 64,the circuit is divided,one branch passing through a reducing resistance 60 and the three .audi'on filaments 37, 40 and 43 and thence: to the terminal 65. The other branch comprises the anti-resonant circuit having the capacity 58 and inductance 59 in parallal and the potentiometer resistance 57. From the poten tiometer are taken ofi the plate circuits of the three audions, the circuit of the first, or detector audion, comprising the plate 38, the

tickler? or feed-back coil 48 and the primary 53 of an audio-frequency transformer for repeating into the next audion through its secondary '54. The plate circuit of the first amplifier tube comprises the plate 41 and the primary 55 of a repeating transformer having a secondary 56 for the second amplifier, the plate circuit of which comprises the plate 44 and the telephone receiver 61.

The antenna 45 has the'usual tuned circuit composed of the variable condenser 46, the inductance 47 and the ground connection 49. An inductive relation exists between the tuning coil 47 and the feedback coil 48. A

condenser 52'is connected around the prii mary 53 of the, first repeating device, in or- I der to bypass the-'radiofrequency component of the 'detected'signal. 501is a grid leak and 51 grid audion. x H. The actionof condenser, for? the detector alternating current, supplied at the terminals 7 and 21 is first rectified by means ofthe I rectifiers. 25 and 26 and is 'thenismoothed out or filteredby the apparatus'shown connected between the rectifiers and the terminals 64:; and 6 5, which operates as described in the.

.said copending application. 7 At these lat;

,ing current components 'of various frequencies, the lowest of which is usually twlce the frequency of the supply. Frequencies higher j ter terminals, the potential consists of a direct current component and small altern'at than this are present in'only'minute quantitie's, due to the greater efficiency of the filter at higher frequencies; This fundamental j frequency is therefore theonly-one which is, ordinarily required to be balanced out by the method of this invention;

component of.theripple'voltageacross the.

. This balancing is accomplished by. a suitable reduction ofthe plate 'terininals,'by meansof theanti-resonant I circuit 58 and. 59., 'whichis anti resonant at 'previously described'in connection with Fig. 11s shown applied to a radlo receiver for twice the frequency of Ithesupply- This application of the invention therefore c-orresponds to that shown in a simplified manner I in Fig. 3. Instead of employing the additional resistance 13' of.Fig.,3, to properly adjust the value of the plate potential, this resistance is incorporated directly into the inductance 59,inFig.'6.

1' In Fig.7 the embodiment of the invention which the power is derived from direct current mains. In this figure and 71 are the terminals of .a commercial direct current 7 lighting system. The filtencomprising the condenser 7 2, theinductances 7 3 land 74 and the second. condenser 75 is of a well known form. "From this point on the receiver circuit' is the. same as that shown in Fig. 6, With 1 elements similarly numbered, with the BX- ce-ptioi' 'thatthe filaments ofthe audionsB'T,

40 and 43 are connected inparallel and thebalancing means is in parallel around the ref.-

' 'sistance 60, instead of in seriesjwi'th the. plate "circuit as in the previous figure; The ballance 76.

' has been fully explained in connection with Fig. 4.

In Fig. 8 the embodiment of theinvention previously described. in connectionwithFig.

is shown as applied to a circuit otherwise the circuit is Ias follows. "The I scribed above both the filaments and plates identical with Fig. 7. and having like parts f similarly numbered. In F g.8 the compensation is-elfected by means of transformers which apply an alternating potential to the grids of theaudions' in proper phase'andamount to offset the potential applied to the plates. In thecircuits of the grids 38, '39- and 4-2 of the andions are connected respectively'the secondaries 83,84: and .85 of'tra' nisformers, the primaries 80, 81 and ofwhich are connected in ser1es,d1rectlyacross the current resistance .ofthese windings is" sufoutput terminalsof the filter; The direct Q ficiently highfs'o thatnoyappreciable direct current is drawn in comparison with the useful direct current load.- Separate transform ers are used for each tube to prevent intercoupling between tubesiand consequent howlingofthe; system.

. In the applications. ofthe invention deoffthe audions are supplied with rectified and filtered alternatlng current or filtered direct current, but the invention may also beemployed in connection with radio receiv crs having thefilaments ofthe audions sup plied with alternating current andthe grids I V of the audions connected to the mid-points r of the potentiometers connected'acrossv the filaments in the manner and for the purpose eliminate disturbances in the plate circuit.

195' disclosed in i United States Patents, No 1 1,432,02200 Heising, October 17, 1922, and 7.. No." 1,195,632, tQ- W'hite, August 22," 1916. i This midpoint-connection does not however due to "the alternating current supplied-to the filament, because the grid voltage-plate current characteristic is not a straight line in p 9 actual tubes. As may be shown both mathe- V .matically'and experimentally the result of.

curvature of the characteristic is to cause a ripple in the output circuit the lowest fre- '7 quency of which is twice the'ofrequency of the currentsupplied to the filament. It has been foundby experiment thattheripple is largely composed of this, second harmonic component, the higher harmonics being comparativelysmall in amplitude.

1 In Fig. 9 there is shownan application of the. invention to a radio receiver of the type shown in Figs. 6, 7 and 8 and having elements correspondingto those of the former figures similarly: numbered. 90 and 91fare the terminals of a commercial alternating 7 current supply, to which is connected the. 1 7 primary 92 of .a transformer. The secondary 93 of the. transformer supplies alternating 1 current at a suitable voltage for the filaments of the audions to thejfilament bus wires 94.

and 95. The filaments 37, 40 andAE; are connected in parallel across the bus wires. Potentiometers 96, 97 and 98 are connected across the filaments,and the grids 36, 39and I 42 are connected to the. mid-pointsof these potentiometers in the mannerdescribed in the l in copending application Serial No. 680,096

referred to above, theseelen ents' being are ranged to form a bridge to the balance points above referred to Heising Patent No.

Secondaries 99 and 1000f the transformer are wound on the same core as the primary 92 and are connected in series with each other. These secondaries supply alternating current at suitable voltage for the plates after the losses in the rectifiers and filter have been deducted. Rectifiers [101 and 102 are arranged as shown for rectifying both halves of the alternating current wave. A storing condenser "103 is connected across the output terminals of the rectifier. The filter consisting of condensers 104 and 106 and inductances 105 and 107 islike that disclosed of'which are connected conductors 109 and ,110 having between them acondenser 108 of suitable value to by-pass the useful audio frequency current in the plate-circuits. Conductor 110 maybe connected to inductance 107 at diiferent points in accordance'with the magnitude of the ripple effect which should I beapplied to the plate circuits.

an output which is free from ripple'effect.

As explained above the grid connections to the mid-points ofthe 'potentiometers do not eliminate disturbancesin the plate. circuits, as would be the case if the grid voltageplate'current characteristic were. a straight line. It has been found that the ripple effect whichis present in the conductors 109 and 110 when the bridge consisting of condensers 104 and 106 and 'inductances 105 and 107 is slightly unbalanced is principally 'of twice the frequency of the alternating cure.

rent supply. Since the amount of ripple ef-' fect in the plate circuits may be controlled by the variablepoint of connection of conductor 110 to inductance 107, the eifectniaybe used to offset the disturbance in the plate circuits caused by the alternating current in the filaments even with the mid-point con nections of the grids. There is thus obtained lVhile certain preferred.embodiments of the invention have been] disclose'dand applications ofthem to typical radio receivers have been shown, it will be understood that the invention may be embodied in other forms and applied to other types of radio'receivers withoutdeparting from the principle there- I claim: 1. The *inethod of as defined inthe appendedclaims;

of counteracting in the i plate circuit of an audiontheeffects of jalterphase relation betwecnthe cathode and plate to the fluctuating current supplied. to the" plate. I

I 2. -.The method of eliminating in the plate I circuit of an audion the; effect of audio frequency variations in potentialof thecurrent energizing the plate and cathode, which coinprises suppi-ying'the cathode-heating circuit with current having audio frequency potential variations of amagnitu'de substantially greater than'the potential variations of the currentsupplied to the plate, thereby to cause variations in the plate circuit substantially .equal to those of the current supplied di rectly to the'platewhile preventing shifting the phase relation between the cathode and plateeflects. 1 p 3. The method .of counteracting, in the plate circuit of an audion the effect ofalter nating components of audible frequency in a s'ingle source of supply which energizes the plate and cathode, which comprises balancing the alternations produced in the plate, cir cuit by thealternating components in the cathode-heating circuit against substantially equaland opposite alternations in the potential applied to the plate circuit.

1. The method of operating an audionv whose plate is energized from a source of direct current having alternating components of audible frequency,-which comprises impressing across the cathode-neat1ng of said audion an alternating voltage derived from said source and in phase andmagnitude effective toproduce in the plate circuit variations in voltage substantiallyequaland 0p-.

posite to those of'the directly-applied plateenergizing current. v

5. The method of energizing an audion which consists inenergizingits plate and cathode with direct'current containing alternating components and-eliminating the efiect' "in the plate circuit of said alternating com; I

ponents by'increasingthe magnitude of the alternating components in the current sup- 7 pliedto the cathode to, cause variations in voltageof the current in the plate circuit 7 substantially equal to the alternating com I ponents in the current supplied'directly to the-plate while preventing shifting ,ofithe effects. p

Apparatus for "energizing an audion,"

comprising'a plate current supply derived j froma source of current having alternating,

components of audible frequency, and means for impressing across the cathode-heating circuitan alternating voltage derived from said source,i'the impedance of said means being such that the phase and magnitudeof 12,5

the applied voltageproduces aneutralization in the plate circuit of the effects of the alternating components of the plate supply.

' 7. In apparatus for eliminating in the plate oircuitof: an audion the effect of variations in potential of the current supplied theplate and cathode, means for "increas- V i ing the magnitude of the" Variations: in" p07 W tential of the currentenergizingsaid cathode to cause variations inthe plate; circuit substantially equal tothose of the current sup: plied directly to the plate and for preventing V shifting-0f the phase relation betweenxthe cathodeand plate effects. 7 p v 8.In apparatus for eliminating in the, i6 plate circuit ofan audion'the effect of variations in potential of the current supplied to the plate andfcathode, a resistance in series With the cathode and aby-pass circuit around 7 the resistance composedfot a 'capacityjand 5 an inductance and resonant atrtlie frequency of saidvariations. p I Y 9. The combinationwith apparatusforenergizing the plate of an audion from a source p of direct current havingalternating compoj 'ne nt's ot-audible: frequency, of means for I passing through: thecatliode-heating circuit an alternating current derivedfromsaid source through said apparatus; the impedanceof said means being such that'the V phase "and magnitude of the alternating cur rent counteracts the eflectin-the plate circuit I of thejalternatingcomponents of the plate 7 current supply. I r V 10. 111" apparatus for energizing an audion, 3 meansfor supplying its plate and'cathode with direct current containing alternating components and means for increasing" the 'magnitudeof the' alternating components in V a the current supplied to the cathodeto'cause Y51I'l2ttlODSflI1 voltage of.tl ie current in thei plate circuitsubs'tantially equal to the alter- I nating components'in thecurrentsupplied 1 directly to the plate and for preventing shifting-ofthe phase relation between the cathode V 7. and plate effects. I f5 J i 7 -;11'. In apparatus for energizing the cath- V ode and plate circuits of an audion from a sourceof directc'urrent-containing periodic V alternating components of audible frequen-* T (5 cy, {the combination ofmeans defining direct f o current pathsfor impressing :upon the-said audion elements from vsaid} source the directcurrent potentials required-for operation'of the'au'dion, of alternating circuit impedance tering thera tio of the alternating to directcomponents in the current supply {to said o cathode to render ngligible' the effect of al- I tern-ating components in thejcurrent supply in;thejcathode-heating current path'foral- I 1 V I to the plate-throughthe otherdirectcurrent 1 i f i l I j ol nitesti'mony whereof I-aflix my signature; I V GEORGE CROUSE 

